Adsorption devices are apparatuses in which a solid adsorbent material sorbs a second medium which boils at a lower temperature, the so-called working medium, in the form of a vapor while releasing heat (sorption phase). In the course of this process, the working fluid evaporates in an evaporator while sorbing heat. After the sorbent material is saturated, it can be re-desorbed when heat at higher temperatures is added to it (desorption phase). At that time, the working medium evaporates from the adsorbent material. The working medium vapor can be recondensed and can subsequently be re-evaporated in the evaporator, etc.
Absorption devices are apparatuses in which a liquid absorbent material is used. The broader term “sorption devices” includes both adsorption and absorption systems.
Adsorption apparatuses for cooling with solid sorbent materials are known from EP 0 368 111 and from DE-OS 34 25 419. Sorbent containers filled with sorbent materials draw off the working fluid medium which forms in an evaporator and sorb it while releasing heat. This heat of sorption must be dissipated from the sorbent. The cooling devices can be used for cooling and heating food products in thermally insulated containers.
WO 01/10738 A1 describes a self-cooling beverage can in which an evaporator is disposed inside and a sorber outside the can. Cooling is initiated by opening a vapor passageway between the evaporator and the sorber. Via the surfaces of the evaporator, the cold generated in said evaporator is transferred to the beverage to be cooled inside the can. The heat generated in the sorbent material is stored in a heat buffer. Compared to a conventional can, this self-cooling beverage can is modified considerably and is expensive to manufacture.
Additional theoretical embodiments of self-cooling assemblies are listed in WO 99/37958 A1. None of these devices can be implemented and produced inexpensively.
U.S. Pat. No. 6,474,100 also describes a self-cooling cooling element disposed on the outer surface of a pouch for holding liquids or bulk products. The sorbent material is enclosed in a flexible, multilayered sheeting material. Contact with the hot sorber filling is reduced to a minimum by insulating and flow materials as well as by heat-storage materials interposed in between. The temperature compensation between the hot sorber filling and the cold evaporator, large surfaces of which face each other, has to be reduced by means of a complicated insulating system.